<select name="om_id" <?php echo $estilo;?>>
    
    <option value=""><?=$t_om;?></option>

    <?php
	
	$sql_om_id = "SELECT * FROM om WHERE status='1' ORDER BY om_nome";
    $res_om_id = sql($sql_om_id);

    while($linha_om_id = mysql_fetch_array($res_om_id)){
    ?>

    <option value="<?=$linha_om_id['om_id'];?>" <?php if($linha_om_id['om_id'] == $om_id) { echo "selected"; } ?>><?=$linha_om_id['om_nome'];?></option>

    <?php } ?>

</select>